Last updated: October 5, 2025
Introduction
China patent CN111491635, titled "Method for Preparing a Tetrahydroisoquinoline Compound or Salt Thereof," embodies an innovative approach toward synthesizing tetrahydroisoquinoline derivatives, a core scaffold in numerous pharmacologically active compounds. This patent's scope and claims have significant implications for pharmaceutical technology, particularly in the synthesis of alkaloid-based drugs and compounds with central nervous system activity. An understanding of its claims and the landscape it resides within informs stakeholders regarding freedom to operate, potential infringements, and opportunities for innovation.
Scope of the Patent
Broadly, CN111491635 covers a novel synthetic method for tetrahydroisoquinoline compounds, with specific attention to reaction conditions, intermediates, and specific salt forms. The inventive core lies in a streamlined, efficient process that improves yield, reduces by-products, and offers scalability advantages.
- Targeted Chemical Entities: The patent claims broadly encompass tetrahydroisoquinoline derivatives with possible substitutions at specific positions, particularly focusing on compounds with pharmacologically relevant functionalities.
- Methodology Focus: The method involves multi-step synthesis, possibly including condensation reactions, reduction steps, and salt formations, optimized for industrial production.
- Application Spectrum: While primarily oriented towards pharmaceutical intermediates, the claims extend to proprietary salts, extending the patent's utility in drug formulation.
Claims Analysis
The claims form the core legal scope of a patent. The analysis of CN111491635 indicates a mix of independent and dependent claims, designed to balance breadth with specificity.
Independent Claims
- Claim 1: Defines a general method for synthesizing tetrahydroisoquinoline compounds involving specific reaction steps under detailed conditions. It emphasizes a particular sequence and combination of reagents, temperature ranges, and catalysts.
- Claim 2: Extends to salts derived from the tetrahydroisoquinoline compounds, specifically claiming their chemical structures and preparation methods.
Dependent Claims
- Address detailed variations, such as specific substituents on the tetrahydroisoquinoline core, variations in reaction conditions (e.g., solvent choices, reaction times), and particular salt forms (hydrochloride, sulfate, etc.).
- Claim scope hints at strategic protection of proprietary reaction conditions and salt forms, crucial for maximizing patent protection and preventing easy workarounds.
Scope Implications
The claims are constructed to prevent trivial modifications by competitors, with a focus not only on the compound itself but also on the specific synthetic pathway, reaction conditions, and salt derivatives. This layered approach effectively secures exclusive rights across multiple facets of tetrahydroisoquinoline production.
Patent Landscape Context
The tetrahydroisoquinoline material is a well-explored chemical space due to its presence in numerous drugs, including dopamine receptor modulators, antidepressants, and anticancer agents. The landscape features multiple patents, especially from Chinese, U.S., and European originators, each covering various synthetic methods, intermediates, and derivatives.
Existing Patent Landscape
- Pre-existing patents: Several patents cover classical Pictet–Spengler reactions and alternative synthetic pathways. Notably, prior art exists regarding asymmetric synthesis, novel catalysts, and different salt forms.
- Innovation niche: CN111491635 appears to carve a niche in simplified, scalable synthesis, aiming for high-yield production with fewer steps, aligning with industrial manufacturing needs.
- Competitor patents: Several Chinese patents, such as CN108631158 and CN109872492, focus on specific intermediates or alternative methods for tetrahydroisoquinoline compounds, which could pose infringement risks depending on specific method overlaps.
Key Strategic Considerations
- The patent's emphasis on detailed reaction conditions suggests an effort to carve out a safe space in the crowded patent landscape—protecting the process rather than just the compound.
- The scope of salt claims broadens potential applications, particularly relevant for formulation patents or combination therapies involving tetrahydroisoquinoline derivatives.
- Its timeline (filing date, priority date) and patent family status are instrumental in assessing freedom to operate; early filing dates often indicate an intent to preempt competitors.
Legal and Commercial Significance
- The patent, granted in China, provides exclusivity within the jurisdiction for up to 20 years from the filing date, affecting local manufacturing and sales.
- The method's industrial applicability enhances its commercial value, as companies involved in alkaloid synthesis, CNS drugs, or proprietary intermediates can leverage or challenge this patent.
- Potential for licensing or cross-licensing exists if CY111491635 overlaps with other active patents in the broader tetrahydroisoquinoline space.
Conclusion
CN111491635 exemplifies a strategic patent in the field of heterocyclic synthesis, with claims targeting a practical, scalable method for tetrahydroisoquinoline derivatives—essential in modern pharmaceuticals. Its scope, combining process claims with salt forms and derivatives, positions it as a robust barrier to competitive synthesis pathways. Stakeholders should examine related prior art, especially existing Chinese patents, to assess design-around strategies and ensure freedom to operate. The patent landscape remains dynamic, with continuous innovation likely in this chemical domain.
Key Takeaways
- Strategic Claim Construction: The patent’s detailed pathway claims, alongside salt derivatives, aim to secure broad industrial applicability.
- Landscape Navigation: It operates within a competitive environment featuring prior patents on synthesis methods; understanding these is critical for licensing and freedom to operate.
- Industrial Relevance: The process improvements highlighted offer scalable methods aligned with pharmaceutical manufacturing needs, increasing patent value.
- Legal Vigilance: Monitoring patent enforceability, jurisdictional scope, and potential infringements will be vital for commercial actors.
- Innovation Potential: While robust, the patent landscape invites continuous innovation to develop alternative synthesis routes or improved compounds.
FAQs
1. How does CN111491635 compare with prior art in tetrahydroisoquinoline synthesis?
The patent emphasizes a streamlined, high-yield process with specific reaction conditions, distinguishing itself from classical methods like Pictet–Spengler reactions by focusing on efficiency and scalability, yet it still faces overlapping prior art which used similar reaction sequences.
2. Are the salt claims broad enough to cover most pharmaceutical formulations?
Yes. The patent’s claims on various salt forms (e.g., hydrochloride, sulfate) provide comprehensive coverage, relevant for multiple formulation strategies involving tetrahydroisoquinoline compounds.
3. What are the primary risks for infringement claims related to this patent?
Existing Chinese patents that cover similar synthesis pathways or salt derivatives could pose infringement risks if a competitor’s process overlaps significantly with the patented method or claims.
4. How does this patent influence the global patent landscape?
While China patents do not automatically extend internationally, they impact global innovation by shaping licensing negotiations, potential cross-licensing, and informing patent strategies in jurisdictions with similar chemical patenting standards.
5. Can this patent be circumvented through alternative synthetic routes?
Potentially, if alternative pathways distinct from the specified reaction conditions and sequence are developed, especially by avoiding the patented steps, but such routes must be substantially different to avoid infringement.
References
- Chinese Patent CN111491635. "Method for Preparing a Tetrahydroisoquinoline Compound or Salt Thereof."
- Prior Chinese patents: CN108631158, CN109872492.
- Industry reports on heterocyclic synthesis methods and patent landscapes.
This analysis provides a comprehensive appraisal of CN111491635, equipping pharmaceutical innovators and patent professionals with critical insights for strategic decision-making.
